Burn swallowing large one (6)
I believe the answer is:
single
'one' is the definition.
(synonyms)
'burn swallowing large' is the wordplay.
I cannot really understand how this works, but
'large' could be 'l' (eg in clothes sizes) and 'l' is found in the answer.
'burn' could be 'singe' (singing is a kind of burning) and 'singe' is found within the remaining letters.
No letters remain.
This explanation may well be incorrect...
Can you help me to learn more?
(Other definitions for single that I've seen before include "Not married, just the one" , "A hit for one run in cricket" , "Just one, or unmarried" , "Solitary or unwed" , "Only one; record" .)